Fuel injection pumps for internal combustion engines

ABSTRACT

An intake and exhaust system is provided for internal combustion engines of the type which employ a main combustion chamber and an auxiliary chamber in communication therewith through a torch nozzle; the main chamber having a valve controlled lean mixture inlet and a valve controlled exhaust outlet; the auxiliary chamber having a valve controlled rich mixture inlet and a spark plug; an intake pipe adapted to conduct a rich mixture to the auxiliary chamber and an exhaust pipe adapted to conduct heated exhaust gasses from the main chamber; the pipes having portions sharing a common heat transferring partition wall to provide a region in which heat is transferred from the exhaust pipe to the rich mixture pipe to heat the rich mixture passing therein; the pipes having portions between the heat exchange region and the main and auxiliary chambers which are separated from each other and joined to the engine in a manner to minimize stress due to temperature change; the pipes being encased in a common housing to provide encompassing heat insulation.

United States Patent Bittelmeyer Sept. 30, 1975 [54] FUEL INJECTION PUMPFOR INTERNAL 3,358,662 12/1967 Kulke 123/139 R ENGINES 3,446,148 5/1969Gllkfil'l 123/139 R 3,620,647 11/1971 Hofer 123/139 BD lnvemorr HallsBittelmeyer, schwalgem, 3,777,731 12/1973 Kobayashi 6t al 123/139 BDGermany [73] Assignee: Robert Bosch GmbH, Stuttgart, Primary ExaminerCharles Myhre Germany Assistant Examiner- Paul Devinsky [22] Ffled; Oct3, 1974 Attorney, Agent, or Firm-Edwin E. Greigg [21] Appl. No.:511,532

ABSTRACT Foreign Application Priority Data A fuel injection pumpmechanism employing a simul- Oct. 3, 1973 Germany 23495810 taneouslyreciprocating and rotating metering piston is provided with reliefchannels which permit the S- 123/139 139 139 AL equalization of theresidual pressures in the various, [51] Int. Cl.2 F02M 39/00sequentially addressed fuel delivery lines leading to 1 Fie fSearCh...123/139 R, 13 F, the engine cylinders. For this purpose, the pump 123/1313 E 1 139 AL piston is provided with a partial annular groove whichconnects the idle fuel delivery channels with one [5 6] References Citedanother. A longitudinal groove further connects UNITED STATES P TENTthese channels to the working pressure chamber of 2,784,670 3/1957 Highet al 123/ 139 BD the fuel lnlectlon Pump- 3,194,225 7/1965 Kemp 123/139R 1 Claim, 3 Drawing Figures US. Patent Sept. 30,1975

FUEL INJECTION PUMP FOR INTERNAL COMBUSTION ENGINES BACKGROUND OF THEINVENTION The invention relates to a fuel injection pump for internalcombustion engines, and more particularly to a fuel injection pump forinternal combustion engines having a metering piston whichsimultaneously rotates and reciprocates within a pump cylinder andwhich, during its rotation, sequentially connects a fuel distributingaperture located on the periphery of the pump cylinder with deliverychannels terminating about the circumference of the pump cylinder. Thefuel delivery channels lead to the individual cylin' ders of theinternal combustion engine. The pump piston is equipped with a partialannular groove through which at least two of the delivery channelscommunicate with one another while fuel delivery takes place through oneof the other delivery channels.

In known fuel injection pumps of this kind, a connecting channel isprovided as a longitudinal channel within the pump which leads from thepump working chamber and terminates in a longitudinal fuel distributinggroove. During the rotation of the pump piston and during its deliverystroke, this groove sequentially communicates with one of the deliverychannels disposed about the circumference of the pump cylinder. Amajority of the remaining delivery channels is in mutual communicationdue to a partial annular groove disposed on the periphery of the pumppiston in 'the same plane as the longitudinal distributing groove. Inthis system, it is only possible to equalize the pressure differencesamong the different delivery lines. If such an annular groove were notpresent, different residual pressures would prevail in the individualdelivery channels and this would result in varying volumes of fuel beingdelivered to the different injection lines, Le. a quantitative spread orscattering of the delivered fuel quantities. The presence of the partialannular groove keeps the residual pressure in the individual deliverychannels constant and a spread of the magnitudes of the injected fuelquantities is prevented. The connecting channel within the pump pistonconstantly communicates with the working chamber of the pump and cannotbe closed off, so that a spread of the magnitudes of the injected fuelquantity, due to different levels of the residual pressure, cannotoccur.

OBJECT AND SUMMARY OF THE INVENTION It is an object of the invention toprovide a fuel injection pump of the kind described above, in which theconnecting channel leading to the distributing aperture can be separatedby a check valve from the working chamber of the pump and extends withinthe pump housing, wherein pressure equalization is achieved among thefuel delivery channels as well as in the connecting channel between fueldelivery strokes of the piston.

This object is achieved, according to the invention, by embodying thedistributing aperture as a longitudinal distributing groove extendingfrom an annular groove in the periphery of the pump piston, and byembodying the connecting channel as a channel extending within the pumphousing, with a check valve being located where the connecting channelexits from the pump working chamber. This connecting channel has a firstoutletaperture in the pump cylinder, located in the vicinity of theeffective region of the annular groove in the piston. The connectingchannel also has a second outlet aperture leading into the pump cylinderwhich may be opened during the suction stroke of the piston by one orseveral longitudinal grooves distributed around the pump pistonperiphery and corresponding in number to the number of fuel distributingchannels. One of the longitudinal grooves extends to and terminates inthe partial annular groove.

In this manner, one obtains a uniform residual pressure in the variousdelivery channels as well as in the connecting channel betweensuccessive delivery strokes, so as to prevent fluctuations in themagnitude of the injected fuel quantity, such as might be caused bydifferent residual pressures in the delivery channels which lie betweenthe various individual injection nozzles and the check valve.

BRIEF DESCRIPTION OF THE DRAWING An exemplary embodiment of theinvention is shown in the drawing and is described in detail below.

FIG. 1 is a longitudinal view, partly in cross section, through aschematic representation of the injection pump according to theinvention;

FIG. 2 is a section through the injection pump depicted in FIG. 1, takenalong the plane IIII; and

FIG. 3 is a section through the injection pump according to FIG. 1,taken along the plane III-III.

DESCRIPTION OF THE PREFERRED EMBODIMENT Turning now to FIG. 1, a housing1 of a fuel injection pump includes a pump cylinder 4 formed by abushing 3, fixedly inserted into the housing of the fuel injection pump.Moving therein is a pump piston 2, driven by means (not shown) in such away that it simultaneously executes an axial reciprocating motion and arotational motion about its longitudinal axis. Due to its rotationalmotion, the piston 2 serves 'as a fuel distributor in that, during itspressure stroke, it delivers the fuel sequentially to individualdelivery channels 5 which are spaced uniformly about the pump cylinder4. The delivery channels 5 lead to the fuel injection valves of theengine (not shown) and are present in the same number as there arecylinders in the internal combustion engine to be supplied with fuel.The cylinder 4 and the face of the pump piston 2 together define a pumpworking chamber 6 which is supplied with fuel during the time that thepump piston 2 executes its suction stroke or occupies its bottom deadcenter position. This fuel is admitted from a pump suction chamber 9through a supply channel 8 and through longitudinal recesses 7. Thenumber of longitudinal recesses 7 is the same as the number of deliverychannels 5 located around the periphery of the pump piston 2; theserecesses terminate in the pump working chamber 6.

A fuel pump 11 delivers fuel from a fuel tank 12 to to the pump suctionchamber 9. A pressure control valve 13 controls the pressure within thesuction chamber 9, in a known manner, so that the pressure in thesuction chamber increases with increasing rpm.

A bore 15 leads from the pump working chamber 6 to a chamber 16. Theterminus of the bore 15 in chamber 16 together with a movable valvemember 17 and a pressure spring 18, disposed within the chamber 16,constitute a check valve assembly 19. A connecting channel 21 extendsfrom the chamber 16, parallel to the axis of the pump within the bushing3 and has a first outlet aperture 22 and a second outlet aperture 23,both of which terminate in the wall of the pump cylinder 4. The firstoutlet aperture 22 is located within the effective working region of anannular groove 25 disposed on the periphery of the pump piston 2 andcommunicates with this groove during the entire delivery stroke of thepump piston. A longitudinal distributing groove 26 also communicateswith the annular groove 25 and, when the pump piston is rotated duringits delivery stroke, the longitudinal distributing groove 26sequentially communicates with one of the several delivery channels 5terminat ing in the pump cylinder 4.

When the pump piston 2 is rotated, the opening of the second outletaperture 23 is controlled by longitudinal grooves 27 disposed in theperiphery of the pump piston, whose number is equal to the number offuel distributing channels. The longitudinal grooves 27 are in mutualcommunication by means of an annular groove 28 disposed on the pumppiston. One of the longitudinal grooves 27 is embodied as an extendedconnecting groove 30 which connects the annular groove 28 with a partialannular groove 31 disposed on the pump piston. The partial annulargroove 21 is located in the region of the termini of the deliverychannels 5 and remains in communication with several different ones ofthese delivery channels 5 during the reciprocating motion of pump piston2, but, as may be seen by comparing FIGS. 2 and 3, it has nocommunication to that particular delivery channel which is, at any onetime, communicating with the longitudinal distributing groove 26.

In a customary manner, the pump piston 2 also includes a longitudinalchannel 33, starting at the pump working chamber 6 and embodied as ablind bore which communicates with the suction chamber 9 through atransverse bore 34 located in that part of the pump piston extendinginto the suction chamber. The terminus of the transverse bore 34 in thepump piston can be opened and closed by an annular slide 35, slidablyand sealingly disposed on the pump piston. The annular slide 35 isdisplaced by an intermediate lever 37 which pivots about a pivotal axis38 under the control of an rpm regulator (not shown), depending on therpm and the load of the engine. For this purpose, the intermediate leveris provided with a spherical head 39 which engages a recess 40 in theannular slide 35.

The method of operation of the injection pump according to the inventionis as follows: during the downward motion of the pump piston 2, i.e.during its suction stroke, the pump piston draws fuel throughlongitudinal grooves 7 and the supply channel 8 into the pump workingchamber 6. The rotation of the pump piston then interrupts thecommunication to the supply channel 8 so that, during the upward motion,i.e. during the delivery stroke of the piston, fuel is delivered fromthe working chamber 6 through the check valve 19 into the chamber 16 foras long as the transverse bore 34 is obturated by the control slide 35.Fuel flows from chamber 16 through the connecting channel 21 and throughthe first outlet aperture 22 into the annular groove 25 on the pumppiston. Thence, the fuel flows through the longitudinal distributinggroove 26 into one of the delivery channels 5. Fuel delivery takes placeuntil the continued axial motion of the pump piston 2 causes the annularslide 35 to reveal the transverse bore 34. From this point on, fuel mayescape from the working chamber 6 through the longitudinal channel 33and the transverse bore 34. Thus, the pressure necessary for deliveringfuel into the delivery channels 5 is not present within the pump workingchamber. The farther the annular slide 35 is moved downwardly by theintermediate lever 37. the sooner the transverse bore 34 is opened andthe smaller is the quantity of fuel delivered into a particular deliverychannel.

During a delivery stroke of the pump piston 2, the longitudinaldistributing groove 26 communicates with one of the delivery channels 5whereas the remaining delivery channels, as may be seen in FIG. 3,communicate with one another via the partial annular groove 31. If thedistributing groove 26 were to close off the various delivery channelsat different pressure levels, different residual pressures would thenprevail in the several delivery channels 5. This would result indifferent quantities of fuel being delivered to the channels insubsequent cycles because, in each case, a certain amount of fuel isrequired in order to equalize the pressure difference at the onset ofeach delivery stroke. In the present case, however, several deliverychannels are in mutual communication via the partial annular groove 31for the purpose of equalizing their residual pressures and preventingsuch pressure differences.

During the suction stroke, after the connection between the longitudinaldistributing groove 26 and the delivery channel is interrupted by therotation of the pump piston, the second outlet aperture 23 is opened byone of the longitudinal grooves 27. Thus, a communication is createdbetween the chamber 16 and the partial annular groove 31, namely throughconnecting channel 21, the longitudinal groove 27, the annular groove 28and the connecting groove 30. In this way, both a majority of thedelivery channels as well as the connecting channel 21 and the chamber16 can be placed in mutual communication for the purpose of pressureequalization. It may be seen from FIGS. 2 and 3 that, when one of thelongitudinal grooves 27 communicates with the second outlet aperture 23of the connecting channel 21, then the longitudinal distributing groove26 is closed off, i.e. does not communicate with any distributionchannel 5.

The result of this arrangement is that, at the beginning of fueldelivery into one of the delivery into one of the delivery channels, thepressure in that channel is the same as that in the connecting channel21 and, thus, variations or a quantitative spread of the magnitudes ofthe delivered fuel quantities due to different residual pressure levelsis reliably prevented.

What is claimedis:

1. A fuel injection pump for internal combustion engines, comprising! a.a housing including a plurality of fuel delivery channels formedtherein;

b. a cylindrical bushing with a central bore, said .bushing beingcontained within the housing and provided with an internal connectingchannel having a first outlet aperture and a second outlet aperture, anda plurality of radial channels communicating with said fuel deliverychannels in said housing;

c. a spring-loaded check valve located in said housing and disposedbetween said central bore and said connecting channel within saidbushing; and

d. a pump piston slidingly disposed within the central bore of saidbushing so as to be capable of simultaneous rotational and reciprocatingmotion, said pump piston including:

i. a first annular groove in the outer surface thereof, so located as tocommunicate with said first outlet aperture of said bushing;

ii. a longitudinal distributing groove in the outer surface thereofcommunicating with said first annular groove, whereby, during therotation of said pump piston, said longitudinal distributing groovesequentially communicates with one of said radial channels in saidbushing, for fuel delivery to one of said fuel delivery channels, duringthe pressure stroke of the piston;

iii. a partial annular groove in the outer surface thereof, so locatedas to establish communication among several ones of said plurality ofradial channels in said bushing;

iv. a second annular groove in the outer sur-

1. The combination with an internal combustion engine having a headstructure of the type which includes a main combustion chamber and anauxiliary combustion chamber communicating through a torch passage, ofan intake and exhaust pipe system comprising: an intake pipe for a richmixture communicating with the auxiliary chamber, an exhaust pipecommunicating with the main chamber, a housing enclosing the intake andexhaust pipes but spaced therefrom, means including a heat transferringpartition wall joining said pipes whereby the rich mixture in saidintake pipe may be heated by exhaust gases conducted through saidexhaust pipe, means attached to the exterior of said housing defining anintake passage communicating with the main chamber, said intake pAssagehaving a heat exchange surface whereby a lean mixture for the lattersaid intake passage may be heated by exhaust gases conducted throughsaid exhaust pipe, a carburetor for delivering a lean mixture at rightangles to said heat exchange surface, and a carburetor for delivering arich mixture at right angles to said heat transferring partition wall.2. The combination with an internal combustion engine having a headstructure of the type which includes a main combustion chamber and anauxiliary chamber communicating through a torch passage, of an intakeand exhaust pipe system comprising: an intake pipe for a rich mixturecommunicating with the auxiliary chamber; an exhaust pipe communicatingwith the main chamber; a housing enclosing the exhaust pipe but spacedtherefrom; means including a heat transferring partition wall joiningsaid pipes whereby the rich mixture in said intake pipe may be heated byexhaust gases conducted through said exhaust pipe; means attached to theexterior of said housing defining an intake passage for a lean mixturecommunicating with the main chamber; the latter said passage having aheat exchange surface whereby lean mixture for the latter said intakepassage may be heated by exhaust gases conducted through said exhaustpipe; a carburetor for delivering a lean mixture at right angles to saidheat exchange surface, and a carburetor for delivering rich mixture atright angles to said heat transferring partition wall.